Owners of other Hyundai, Genesis or Kia vehicles such as the Sonata, Accent, Veloster, Ioniq, Kona, Nexo, Venue, Tucson, Santa Fe, Palisade, G70, G80, G90, Soul, Sportage, Niro, Sorento, Telluride, Rio, Forte, Optima, Stinger, Cadenza, K900, Sedona and Seltos may also find these DIY instructions to be helpful.

The compatible replacement coin cell battery (also known as a "button" or "watch" battery) is part number CR2032 which is available from a variety of manufacturers such as Panasonic, Duracell, Energizer, Sony and Maxell.

The only tool needed to access and replace the battery is a small flat head screwdriver or a small plastic pry bar tool.

(If your Elantra is a higher trim level with the optional all-in-one key fob with the swing out "switchblade" style ignition key, check out my tutorial for the Hyundai Tucson Key Fob Battery Replacement Guide.)

The first step is to separate the key ring and ignition key from the fob.

Insert the flat head screwdriver or a plastic pry bar tool into the small notch.

Gently rotate the screwdriver to pry apart the two halves of the fob housing.

You may need to re-insert the screwdriver in several locations to fully pop open the key fob case.

Gently lift the rubber piece with the molded buttons out of the fob.

Pull the green circuit board out of the rear half of the fob case.

Try to avoid scratching the circuit board, damaging the plastic battery socket or bending the electrical metal contacts.

The OEM (original equipment manufacturer) battery in this 2018 Elantra was a Panasonic CR2032 3V coin cell.

The old battery might be covered in a thin layer of dielectric grease. You could choose to transfer some of the grease to the new battery or not. I haven't had an issue with just installing new clean batteries without using dielectric grease.

Gently lower the remote control unit into the rear half of the fob housing with the battery holder facing down and the three small silver metal buttons facing up towards you.

Line up the front half of the fob assembly over the rubber buttons.

Carefully pop together the two halves of the fob.

Re-attach the key ring, ignition key and your other keys to the fob assembly.

To test the new battery, stand near your Elantra and press the "Unlock" or "Lock" buttons.

If the new battery is working properly, you should see the parking lights flash and also hear the door locks opening and closing.

(The fob should not need to be reprogrammed. Just replacing the battery should not clear the original programming.)

Be sure to write down the battery change in your vehicle's service records.

For more, please check out all of my 2017-2020 Hyundai Elantra DIY Repair & Maintenance Guides.